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Star Trek: An Interview with Astrophysicist Anthony Soulain

With clear skies and big telescopes, Chile is seventh heaven for astronomers, attracting these scientists of the stars from all over the world to work here. But what is the life of an astronomer really like? Cascada interviewed Anthony Soulain, a budding French astrophysicist studying his master’s degree in Santiago. He debunks many myths about what astronomers do, tells us why Chile is the best country for astronomy, reminds us why astronomy is important and gives us a peek into Cerro Paranal with his stunning photos. Buckle up for a trip to the stars, with some serious science along the way!

There’s a popular image of the astronomer as a night owl who looks at the heavens through a telescope when everyone else is sleeping. Is this true? What does an astronomer actually do?

There are different kinds of astronomers, and they do different kinds of work. We can divide astronomers into three types: observers, data analysts and theoreticians. Observers fit more closely with that image which you described. In contrast, data analysts and theoreticians seldom look at the sky through telescopes. Analysts work with the information collected from telescopes, converting the raw data into scientifically useful data, while theoreticians develop theories and models. These astronomers sometimes collect data at an observatory as well, but maybe for a period of one week annually. For the rest of the year, they work on the data they’ve collected - during the day! The job of the observers, on the other hand, is to collect data on behalf of other analysts and theoreticians, and that’s why they spend so much time at the observatories. In general though, the life of an astronomer in 2015 is not spent behind a telescope. Indeed, I’d say about half of the astronomers never use a telescope. Some of my friends hate using it because they find it boring.

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Night-time Observation on Cerro Paranal

Can you tell us more about what kind of data is collected through the telescopes?

Again, there are all kinds of data collected, such as images of astronomical objects, the stars’ electromagnetic spectrum, luminosity etc., a lot of numbers and graphs. Another common misconception about the astronomer’s work is that they see stuff through the telescope. Actually, looking at things with our eyes is a minor part of modern astronomy. The amazing pictures of galaxies and supernovae  that you see in the press have little to do with our work. In fact, you wouldn’t be able to see those beautiful colours even if you travelled to that part of space. The colours are chosen, rather, to represent something, say red for hydrogen or green for helium. The photos are usually composed of a number of images taken with detectors sensitive to different wavelengths. So the pictures “seen” by these detectors aren’t even visible to the human eye, since the visible range is a very small part of the electromagnetic spectrum. However, when the composite image is made, astronomers choose beautiful colours to represent these invisible images, like red for infrared wavelengths or blue for ultraviolet, so in the end we get these attractive pictures of the cosmos.

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That's what a cutting-edge telescope looks like!

So what type of astronomer are you?

I’m a data analyst. My research focuses on a type of stars known as cepheids. They are pulsating stars that expand and contract periodically, quite rare in the universe. But they are very important because they can help us calculate distances. How do you know how far away a star is when everything you see resembles dots on a black screen? Luckily, cepheids provide a reliable method for calculating distances. There is a mathematical relationship, discovered by female astronomer Henrietta Leavitt in 1912, between the absolute luminosity of a cepheid (how much light it emits) and its period of expansion and contraction. So using a telescope, we can measure the period of a cepheid. Then we can work out its absolute luminosity. Finally, we measure its apparent luminosity (how bright it appears as seen from Earth). By the difference between the absolute and apparent luminosity, we can work out how far the star is away from Earth. My goal is to improve this method by looking at other parameters, such as the star’s velocity, and develop alternative models based on this important mathematical rule.

An exciting development will be the launch of the new telescope Gaia into space. This telescope will use a different method to measure distances, known as the parallax method. What’s parallax? When you move, the objects in front of you appear to move too, but the objects closer to you move more than those that are far away. Using this principle, we can measure the distance between us and faraway astronomical objects, since the Earth moves in its orbit. Gaia works on this principle, and it’s very accurate. Imagine a telescope that allows you to see seeds on Earth from the International Space Station. That’s how accurate Gaia is, only that it looks at objects much further away. Using data from Gaia, we will be able to make comparisons with our present model based on cepheids.

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Cerro Paranal is located in the lonely but spectacular landscape of Atacama

Why did you choose to come to Chile?

Chile is one of the best places for astronomers. Cerro Paranal, in the north of Chile, has the biggest telescopes in the world. The skies of northern Chile are best for astronomical observation, rivalled only by Hawaii. There is no light pollution, little disturbance in the atmosphere thanks to the protection of the ocean and the Andes, and the weather is perfect, suitable for observation about 80 - 90% of the year.

Many of the astronomers who chose to come to Chile are keen on observation, even if they are usually analysts or theoreticians. Cerro Calan, an observatory near Santiago, is a place where students are trained in telescope use. I myself also like observing the sky, making Chile an ideal place for me.

Is there anything that makes the Chilean sky unique?

As Chile is in the Southern Hemisphere, you can see stuff from here that cannot be seen from Hawaii. Most importantly, the galactic centre of the Milky Way is visible. The centre is where the galaxy is very dense, where many objects are concentrated. For this reason, Chile is world-class for its great position in the South. Astronomy was born in the Northern Hemisphere, but the best equipment is now in the South because an unexplored sky has been opened up down here.

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A panorama of Paranal

What does the Chilean government do to support astronomy?

Chile does quite a lot to support astronomy. Chilean astronomers are well-paid, sometimes earning more than their European counterparts. They also get allocated 10% of the observation slots available at Cerro Paranal. The government has also given free land for the European Southern Observatory (ESO) to build its institute.

Such help is really needed because not everyone realises the importance of astronomy. For many, spending billions of dollars to unlock the mysteries of the universe doesn’t make a lot of sense, but many of our technological breakthroughs wouldn’t have become reality without astronomy. An example is GPS. Recently, Brazil backed out from joining ESO. If they had joined, we would have received enough money for the construction of a huge telescope at Cerro Paranal. This new telescope would measure 39m in diameter, but its construction is going to be difficult and expensive. In astronomy, money equals more discovery, because with better equipment, we’re bound to see more. Sadly, it’s hard to get the public to see the relevance and importance of astronomy.

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Anthony posing in front of the best telescopes in the world

Many thanks to Anthony for his insightful look into the life of a modern astrophysicist! We wish you all the best for your career!

Now why don't you take the advice from astronomers and head to Atacama with Cascada for the best stargazing on Earth?